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Instructions
To rotate, click on the DNA molecule, hold down and drag.

To zoom in and out, click and hold down on the magnifying glass icons.

Key
Adenine, Thymine base pair
Guanine, Cytosine base pair
Helical backbone

'The key to life'
DNA's double helix holds the key to life. The secret discovered by Watson and Crick in 1953 is that there are four possible types of rung on the ladder formed by the double helix.

There are A-T rungs, where adenine bonds to thymine, T-A rungs where thymine bonds to adenine, C-G rungs where cytosine bonds to guanine, and G-C rungs where guanine bonds to cytosine. No other combinations are possible due to the shape of the four substances.

The outer helices of the DNA molecule, coloured blue on our model, are made up of a chain of circular sugar molecules, each bearing a phospate group. Biochemists call the helices "the sugar-phosphate backbone".

There are about 2.85 billion rungs on the ladder of human DNA. The initial letters of the rungs spell out the sequence of the human genome, the blueprint for each generation of new life.

The DNA molecule is 65k and should take no more than 60 seconds to download over a 56k modem.

It is designed to be played on computers with at least a 400Mhz processor and users with slower machines may experience performance problems.

If it appears to be running slowly try closing down any other applications you may be running.

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